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Biomedical subjects

S G Hamilton

Publications and source records attributed to S G Hamilton.

15 recordsLinked to original sources
PubMed1990

Lipid-coated ultrastable microbubbles as a contrast agent in neurosonography.

Lipid-coated microbubbles can be synthesized from selected lipid monolayer systems for use as ultrasonic contrast. These microbubbles have the property of longevity of weeks in vitro (ultrastability) and longevity of hours in vivo. The bubbles can be manufactured with a mean diameter of approximately 2 microns in a tight diameter distribution; all are less than 6 microns and 99% are smaller than 4.5 microns. The current study compared the in vivo survival characteristics of these lipid-coated microbubbles with microbubbles produced by saline. The comparison was made in the rat brain using direct intraparenchymal injections and injections into a previously created cyst/coagulum. The echogenic enhancement by the lipid-coated microbubbles persisted in vivo for over 24 hours in both the intraparenchymal environment and in the cyst/coagulum. The saline bubble echos were not detectable by 3 hours in a cyst/coagulum, and not detectable in the parenchyma after 2 hours. The sonographic characteristics and longevity of lipid-coated microbubbles make this agent a potentially useful clinical contrast material for neurosonography.

Animals↗
PubMed1986

Designing an implant by CT scanning and solid modelling. Arthrodesis of the shoulder after excision of the upper humerus.

Techniques are described by which metal implants can be designed and produced to fit precisely a bony site at a subsequent operation. CT scans and solid modelling were used to produce an accurate three-dimensional representation of the surface of the bone. These techniques were applied to the production of an internal fixation device for shoulder arthrodesis after the resection of a neoplasm of the proximal humerus. The reconstruction utilised a free vascularised fibular graft between the scapula and the distal humeral remnant, fixation being secured with the custom-made implant.

Adolescent↗
PubMed1986

Comparison of antipseudomonad activity of chlorine dioxide/chlorous acid-containing gel with commercially available antiseptics.

A chlorine dioxide-containing gel was compared with 3 commercially available antimicrobials and 1 antibiotic intended for topical use. This gel was tested at 0.5 X and 4 X and was found to be more effective as a 4 X gel in treating Pseudomonas aeruginosa-infected excised wounds on mice. To further compare this gel with other antiseptics, a murine bioassay was developed. This wound model consisted of an excised cutaneous wound on the dorsum of mice which were irradiated (800 rad) and inoculated with P aeruginosa at 10-fold dilutions, from 10(-2) to 10(-10). The wounds were observed for latency of infection or mice survival time as a function of concentration of viable organisms remaining after treatment. The advantage of this model was demonstrated where a standard curve based on latency did not consume as many test subjects and yet provided an estimate of viable organisms in each wound. In this model, the chlorine dioxide-containing gel was more active than were preparations of providone-iodine, chlorhexidene, or silver sulfadiazine and was similar to polymyxin-bacitracin-neomycin ointment as a topical antiseptic. The effectiveness of the tested gel was reduced if delays in treatment were longer than 1 hour.

Animals↗
PubMed1986

Controlled wound repair in guinea pigs, using antimicrobials that alter fibroplasia.

The repair processes of incised wounds depend, in part, on fibroplasia induced by soluble mediators from monocytic macrophages. Two topical antimicrobials were evaluated, each of which effectively controlled wound sepsis and yet each had widely different effects on fibroplasia and wound strength. Paired-incision dermal wounds on the flanks of guinea pigs were treated with a substance containing reactive chlorine (Alcide) or with a compound that is a mixture of two surfactants. One side of each guinea pig was treated with one of the antimicrobials (treated wounds); the opposite side was treated with isotonic saline solution (control wounds). At 7, 10, and 16 days after surgery, tensiometric measurements of C31G (a surfactant)-treated wounds were 99%, 139%, and 195% of control wound values, respectively. Alcide-treated wounds were 76%, 58%, and 88% of control wounds, respectively. Wounds treated with chlorhexidine had reduced strength at 7 days (73%) and at 10 days (78%), but by 14 days, they were similar to control wounds (94%). The main difference between the wounds was the amount of collagen formation. Alcide-treated wounds incorporated less than 50% of the amount of 14C-proline than did the wounds treated with C31G. However, Alcide-treated wounds epithelialized as rapidly as did control wounds, and had minimal scar formation. Microscopic evaluations indicated greatly reduced inflammatory infiltrates in Alcide-treated wounds, indicating that reduced wound strength may be associated with lack of fibroblast-stimulating activity by monocytes.

Animals↗
PubMed1985

Defective macrophage function in wound repair of P/J mice.

The strength of healing full-thickness incised dermal wounds in P/J mice was less than that of CD-1 mice although the strength of intact skin was similar for each strain. Five days after surgery, P/J mice had wounds with tensile strengths of 65 +/- 18g while CD-1 mice had wounds with strengths of 85 +/- 15g. The wound breaking strength of P/J mice was restored to normal values (86 +/- 18g) by administering glucan. The consequence of defective monocytes in wound repair is discussed in reference to P/J mice.

Animals↗
PubMed1977

The initial phase of gastric emptying before and after vagotomy and pyloroplasty.

The initial phase of gastric emptying of solid food was monitored with the use of a gamma camera and on-line computer facilities. In normal subjects a consistent pattern was seen comprising an early delay in the onset of emptying ("plateau"), followed by an exponential decay curve. After vagotomy the plateau was lost, and the exponential pattern of emptying commenced once the stomach was full. There was no evidence of sudden "dumping" of contents from the stomach. The overall rates of emptying as measured by the half emptying time (T 1/2) were the same in normal and postvagotomy subjects.

Duodenal Ulcer↗
PubMed1976

Multiple hyperplastic inflammatory polyps complicating quiescent ulcerative colitis.

A patient with well-controlled and currently asymptomatic ulcerative colitis had II unusually large polypoid lesions in his colon demonstrated by barium enema X-ray examination and colonoscopy. Previous histological descriptions of inflammatory polyps did not adequately describe their morphology, and the term "hyperplastic inflammatory polyp" is suggested.

Adult↗
PubMed1976

Continuous monitoring of the effect of pentagastrin on gastric emptying of solid food in man.

By continuous monitoring of a solid meal labelled with a radiopharmaceutical it has been possible to determine the effects of drugs on gastric emptying and motility during a single study. Predictably hyoscine delayed, and bethanechol increased, the rate of gastric emptying. Pentagastrin initially produced marked antral activity resulting in a physiological stricture and subsequent delay in the overall rate of gastric emptying. Fundal motility was unaffected though reflux from the antrum occurred.

Gastrointestinal Motility↗